Redox Emulsion Polymerization of Terpenes: Mapping the Effect of the System, Structure, and Reactivity

Synthesis of biobased polymers from renewable feedstocks has been the focus of research on sustainability. The family of acyclic terpenes, particularly β-myrcene, β-ocimene, and β-farnesene from renewable feedstocks, imparts a classical chemistry close to isoprene (unsaturated hydrocarbon from petroleum). In this work, redox emulsion polymerization of these terpenes was carried out. The polymerization of β-myrcene produced a high molecular weight rubbery polymer ( M n = 1.68 × 10 5 Da) with a maximum yield of 65%. The spectroscopic measurements showed that polymyrcene predominantly contained a 1,4-microstructure. The polymyrcene from the best redox initiator system was characterized in detail. Its microstructure was established using 1D and 2D NMR spectroscopy. Polymyrcenes synthesized using different recipes displayed a glass transition temperature from −70 to −58 °C, indicating a rubbery nature. However, β-ocimene and β-farnesene polymerization yielded low molecular weight polymers with preferable 1,4-addition products. Density functional theory provided the ground state-optimized structure of terpenes.